Safety system



April 1,

ROHKOHL 1,752,852

SAFETY SYSTEM Filed Jan. so, 1928 Invent 0v:

Wilhelm Rohkohl by I His Attorn ey Patented Apr. 1, 1930 UNITED STATES PATENT OFFICE WILHELM BOHKOHL, OF POTSDAM, GERMANY, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK SAFETY SYSTEM Application filed. January 30, 1928, Serial No.

The invention relates to safety systems for electric supply circuits, such as used in railway operation and the like, and has for its object in the case of great excess currents,

short-circuits and the like, to protect the electrical apparatus, such as traveling vehicles and their arrangements, operated on a high tension system, so that the ordinary overload faults are overcome through the protective devices located in the vehicle, while in case of heavy short circuit faults or the like the switching-oi of the system is brought about by the safety devices at the substation power house or at another appropriate point.

The invention consists particularly in the arrangement of additional switching contrivances on a safety device consisting of a safety fuse or of an ordinary overload current switch. At some distance from the arcbreaking members special auxiliary poles are in this case provided onto which is conducted the are occurring during short circuits or the like which cannot be extinguished alone through drawing out by means of the breaking members. These auxiliary poles are con nected with one another through a resistance and the coil of a short-circuit switch or of another switch. In case a short-circuit switch is used this has a further winding which is fed by the short-circuit current conducted through the switch contacts and which has for its object to keep the switch closed until the system is cut off from the station.

In the single figure of the drawing an example of a circuit arrangement embodying the invention is represented diagrammatically.

Referring to the drawing the high tension system is indicated with reference numeral 1, the current collector of a vehicle with reference numeral 2 and the safety cut-out fuse with reference numeral 3, this fuse being provided with arc-breaking horns f and 5. As can be seen, near or behind the arc-breaking members 4; and 5 respectively auxiliary poles 6 and 7 are located. These poles 6 and 7 are electrically connected with each other through the coil 8 of the short-circuit switch 9 and the resistance 10, but they have no electric connection with the arc-breaking mem- 250,630, and in Germany February 24, 1927.

bers 4 and 5. In front of the safety fuse 3 a line 11 branches off which conducts to earth through a second coil 12 and the contacts of switch 9. The method of working of the arrangement is as follows:

In case of a certain excess current which runs from the system 1 through the current collector 2 and the safety cut-out 3 in the direction of the arrow, the safety cut-out fuses, the arc arising through this travels upwards on the two horns 4 and 5, and, in a given case, extinguishes before reaching the vicinity of the auxiliary poles 6 and 7 If the overload is very great then the arc can jump over from the horns at and 5 onto the auxiliary poles 6 and 7 so that from each horn an arc leads to the corresponding pole. Then parallel to the are there arises a current path which runs from the system 1 through the current collector 2, the left horn 4, the left auxiliary pole 6, the coil 8 of the short-circuit switch 9, the resistance 10, the right auxiliary pole 7 and the right horn 6 in the direction of the arrow. The switch 9 is thereby closed and now there is established a direct short circuit from the system over the line 11, the coil 12 and the contacts of the switch 9 to earth, which unloads the safety fuse and the lines and apparatus to be protected by it.

In case the safety devices arranged in the so station have not previously come into effect, by means of this short-circuit current they are sure to respond so that the system is cut off and becomes currentless and the arc is extinguished. After this, since its coils then become currentless, the short-circuit switch, by means of the spring 9 or the like, is again moved into its open position. The second coil 12 of switch 9 is for preventing the switch after it has been caused to close through the action of coil 8 from suddenly returning into the open position when the arc is extinguished and thereby interrupting the current path leading over the auxiliary poles. The coil 12 has therefore for its object to keep the switch closed until the system 2 has become currentless.

In place of the short-circuit switch, a second switch can be arranged in series with the safety fuse or the switching apparatus whose control is effected through the aforesaid parallel circuit. This second switch may serve for interrupting the main circuit or for inserting a resistance.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. A safety system including a safety cutout, arc-breaking members associated wit-h said cut-out, auxiliary poles adjacent said arc-breaking members respectively and out of the path of normal arc therebetween, and an electrical connection between said poles forming a parallel circuit to the are when an abnormal arc jumps over to said auxiliary poles.

2. A safety system comprising a cut-out,

arc-breaking members associated with said cut-out, auxiliary poles adjacent said arcbreaking members respectively and out of the path of the normal arc therebetween, an electrical connection between said poles including a current responsive device, said electrical connection forming a parallel circuit to the are when an abnormal arc jumps over to said auxiliary poles, and circuit control means operated by said current responsive device.

3. A high potential safety system comprising a pair of diverging horns arranged to constitute arc-breaking members, a current responsive cut-out connected across said horns, a pair of auxiliary poles arranged out side of the normal arcing space between said horns, an electrical connection between said auxiliary poles forming a short circuit for the are when an abnormal arc jumps over to said auxiliary poles, and current responsive control means included in said circuit.

4. Aprotective system for a high potential circuit comprising a current responsive cut-out in said circuit, diverging horns on opposite sides of said cut-out constituting arc-breaking members, a pair of auxiliary poles, an electrical connection between said poles including resistance, said poles being arranged outside of the normal arcing space between said horns so that an abnormal arc in expanding jumps over to said poles and is by said switch, said connection leading to a point in front of said cut-out.

6. A high potential safety system comprising a cut-out, arc-breaking members associated with said cut-out auxiliary poles adjacent said arc-breaking members respectively, an electrical connection between said poles forming a parallel circuit to the are when the arc jumps over to said auxiliary poles, a current responsive device included in said connection, an electric switch operated to closed position by said current responsive device, a ground connection controlled by said switch, said connection leading to a point in front of said cut-out, and an operating Winding for said switch included in said ground connections. I

In witness whereof, I have hereunto set my hand this 7th day of January, 1928.

VVILHELM ROHKOHL.

thereby shortcircuited through said connection, current responsive actuating means included in said connection, and control means for said circuit operated by said current responsive means. V

5. A high potential safety system comprising a cut-out, arc-breaking members associated with said cut-out, auxiliary poles adjacent said arc-breaking members respectively, an electrical connection between said poles forming a parallel circuit to the are when the arc jumps over to said auxiliary poles, a current responsive device included in said connection, an elect -ic switch operated to closed position by said current responsive device, and a ground connection controlled 

